1. Field of the Invention
The present invention relates generally to rear proton screens, and more particularly to a new strap design to reduce edge reflections in tiled rear projection screens.
2. Description of the Related Art
Video walls comprising multiple tiled video screens are known in the art, wherein multiple individual video display devices (i.e. cubes) are vertically and horizontally stacked to create a cube wall (e.g. see U.S. Pat. No. 5,467,221 (Iwahara et al); U.S. Pat. No. 4,866,530 (Kalua); U.S. Pat. No. 4,919,518 (Ogino et al) and U.S. Pat. No. 5,011,277 (Ogino et al). The conventional cube wall is arranged with cubes placed squarely one on top of another and side-by-side. The video screens are closely edge aligned, both vertically and horizontally, to provide a uniform video wall with an apparently seamless structure. Light distribution is an important component in creating a uniform wall and is controlled through specific optical structures within the various screens.
Each cube comprises a metal frame for housing the optical structures and a rear proton video screen mounted on a clear, acrylic surface. A thin, flexible acrylic strap extends around top, bottom and side edges of the frame adjacent the screen edge to provide structural integrity to the cube. The strap is bonded to the mounting surface via an open channel created by a rabbet cut in the acrylic strap adjacent the screen. The rabbet cut creates a channel that functions as a reservoir into which liquid methylene chloride is permitted to flow during bonding.
One disadvantage of such video screens is the occurrence of first and second order reflections at the edges of the screen. First order reflections result from optical interference as incident light intercepts the channel region where the dear acrylic mounting surface is bonded to the strap. Second order reflections occur when the projection image is over-scanned beyond two pixels, such that the projected light becomes incident on the inside edge of the strap.